Vehicle security systems are widely used to deter vehicle theft, prevent theft of valuables from a vehicle, deter vandalism, and to protect vehicle owners and occupants. A typical automobile security system, for example, includes a central processor or controller connected to a plurality of vehicle sensors. The sensors, for example, may detect opening of the trunk, hood, doors, windows, and also movement of the vehicle or within the vehicle. Ultrasonic and microwave motion detectors, vibration sensors, sound discriminators, differential pressure sensors, and switches may be used as sensors. In addition, radar sensors may be used to monitor the area proximate the vehicle.
The controller typically operates to give an alarm indication in the event of triggering of a vehicle sensor. The alarm indication may typically be a flashing of the lights and/or the sounding of the vehicle horn or a siren. In addition, the vehicle fuel supply and/or ignition power may be selectively disabled based upon an alarm condition. A typical security system also includes a receiver associated with the controller. The receiver cooperates with one or more remote transmitters typically carried by the user and which are used to arm and disarm the vehicle security system, for example. Other remote control features, such as locking or unlocking vehicle doors may also be performed.
The alarm indication provided at the vehicle is important to the overall effectiveness of the security system. For example, a weak alarm indication may do little to deter a would-be thief. A thief may also be more likely to target a vehicle when the vehicle is among hundreds of vehicles in a large parking lot, for example. In such a situation, the thief may be comforted in knowing that the alarm indication will not be identified by the vehicle's owner, since many audible alarm indications are generic.
U.S. Pat. No. 5,079,538 to DeFino et al. discloses an approach to address the shortcomings of generic sounding sirens or alarms. In particular, the patent discloses a processor which can be programmed to provide various multi-toned alarm sounds. Spaced between these multi-toned alarm sounds are a series of repetitive monotones, each of short duration. The number of repetitive monotones is programmed into the processor by the installer of the alarm.
Omega Research & Development, Inc. of Douglasville, Ga. offered a vehicle security system under the model designation AL-800 beginning in 1989 that gave a user the option to select a sequence of six different sound patterns to be used as the audible alarm indication. In other words, six sound patterns were stored in memory and played back in a user selected sequence, one after the other, to thereby create a more unique alarm.
Unfortunately, despite advances in vehicle security system technology, especially as relates to the audible alarm indication, a would-be thief may still ignore the threat of discovery from a conventional audible alarm indication. As more and more cars are equipped with security systems, and as false alarms are a common occurrence, the sound of a conventional vehicle security system alarm maybe unlikely to deter a would-be thief.